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Martin de Fourchambault E, Callens N, Saliou JM, Fourcot M, Delos O, Barois N, Thorel Q, Ramirez S, Bukh J, Cocquerel L, Bertrand-Michel J, Marot G, Sebti Y, Dubuisson J, Rouillé Y. Hepatitis C virus alters the morphology and function of peroxisomes. Front Microbiol 2023; 14:1254728. [PMID: 37808318 PMCID: PMC10551450 DOI: 10.3389/fmicb.2023.1254728] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/07/2023] [Indexed: 10/10/2023] Open
Abstract
Despite the introduction of effective treatments for hepatitis C in clinics, issues remain regarding the liver disease induced by chronic hepatitis C virus (HCV) infection. HCV is known to disturb the metabolism of infected cells, especially lipid metabolism and redox balance, but the mechanisms leading to HCV-induced pathogenesis are still poorly understood. In an APEX2-based proximity biotinylation screen, we identified ACBD5, a peroxisome membrane protein, as located in the vicinity of HCV replication complexes. Confocal microscopy confirmed the relocation of peroxisomes near HCV replication complexes and indicated that their morphology and number are altered in approximately 30% of infected Huh-7 cells. Peroxisomes are small versatile organelles involved among other functions in lipid metabolism and ROS regulation. To determine their importance in the HCV life cycle, we generated Huh-7 cells devoid of peroxisomes by inactivating the PEX5 and PEX3 genes using CRISPR/Cas9 and found that the absence of peroxisomes had no impact on replication kinetics or infectious titers of HCV strains JFH1 and DBN3a. The impact of HCV on peroxisomal functions was assessed using sub-genomic replicons. An increase of ROS was measured in peroxisomes of replicon-containing cells, correlated with a significant decrease of catalase activity with the DBN3a strain. In contrast, HCV replication had little to no impact on cytoplasmic and mitochondrial ROS, suggesting that the redox balance of peroxisomes is specifically impaired in cells replicating HCV. Our study provides evidence that peroxisome function and morphology are altered in HCV-infected cells.
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Affiliation(s)
- Esther Martin de Fourchambault
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
| | - Nathalie Callens
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
| | - Jean-Michel Saliou
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, UAR CNRS 2014 - US Inserm 41 - PLBS, Lille, France
| | - Marie Fourcot
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, UAR CNRS 2014 - US Inserm 41 - PLBS, Lille, France
| | - Oceane Delos
- MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
- I2MC, Université de Toulouse, Inserm, Université Toulouse III – Paul Sabatier (UPS), Toulouse, France
| | - Nicolas Barois
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, UAR CNRS 2014 - US Inserm 41 - PLBS, Lille, France
| | - Quentin Thorel
- Université de Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011 - EGID, Lille, France
| | - Santseharay Ramirez
- Faculty of Health and Medical Sciences, Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital Hvidovre and Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Jens Bukh
- Faculty of Health and Medical Sciences, Copenhagen Hepatitis C Program (CO-HEP), Department of Infectious Diseases, Copenhagen University Hospital Hvidovre and Department of Immunology and Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Laurence Cocquerel
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
| | - Justine Bertrand-Michel
- MetaToul-MetaboHUB, National Infrastructure of Metabolomics and Fluxomics, Toulouse, France
- I2MC, Université de Toulouse, Inserm, Université Toulouse III – Paul Sabatier (UPS), Toulouse, France
| | - Guillemette Marot
- Université de Lille, Inria, CHU Lille, ULR 2694 - METRICS: Évaluation des technologies de santé et des pratiques médicales, Lille, France
| | - Yasmine Sebti
- Université de Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1011 - EGID, Lille, France
| | - Jean Dubuisson
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
| | - Yves Rouillé
- Université de Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U 1019 – UMR9017 – CIIL – Center for Infection and Immunity of Lille, Lille, France
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Desmarets L, Callens N, Hoffmann E, Danneels A, Lavie M, Couturier C, Dubuisson J, Belouzard S, Rouillé Y. A reporter cell line for the automated quantification of SARS-CoV-2 infection in living cells. Front Microbiol 2022; 13:1031204. [PMID: 36246297 PMCID: PMC9558224 DOI: 10.3389/fmicb.2022.1031204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/16/2022] [Indexed: 11/13/2022] Open
Abstract
The SARS-CoV-2 pandemic and the urgent need for massive antiviral testing highlighted the lack of a good cell-based assay that allowed for a fast, automated screening of antivirals in high-throughput content with minimal handling requirements in a BSL-3 environment. The present paper describes the construction of a green fluorescent substrate that, upon cleavage by the SARS-CoV-2 main protease, re-localizes from the cytoplasm in non-infected cells to the nucleus in infected cells. The construction was stably expressed, together with a red fluorescent nuclear marker, in a highly susceptible clone derived from Vero-81 cells. With this fluorescent reporter cell line, named F1G-red, SARS-CoV-2 infection can be scored automatically in living cells by comparing the patterns of green and red fluorescence signals acquired by automated confocal microscopy in a 384-well plate format. We show the F1G-red system is sensitive to several SARS-CoV-2 variants of concern and that it can be used to assess antiviral activities of compounds in dose-response experiments. This high-throughput system will provide a reliable tool for antiviral screening against SARS-CoV-2.
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Affiliation(s)
- Lowiese Desmarets
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Nathalie Callens
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Eik Hoffmann
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Adeline Danneels
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Muriel Lavie
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Cyril Couturier
- INSERM U1177-Drugs and Molecules for Living Systems, Institut Pasteur Lille, Université de Lille, Lille, France
| | - Jean Dubuisson
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Sandrine Belouzard
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
| | - Yves Rouillé
- CNRS UMR 9017, INSERM U1019 Centre d’Infection et Immunité de Lille (CIIL), Institut Pasteur de Lille, Université de Lille, Lille, France
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3
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Callens N, Brügger B, Bonnafous P, Drobecq H, Gerl MJ, Krey T, Roman-Sosa G, Rümenapf T, Lambert O, Dubuisson J, Rouillé Y. Morphology and Molecular Composition of Purified Bovine Viral Diarrhea Virus Envelope. PLoS Pathog 2016; 12:e1005476. [PMID: 26939061 PMCID: PMC4777508 DOI: 10.1371/journal.ppat.1005476] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 02/07/2016] [Indexed: 11/17/2022] Open
Abstract
The family Flaviviridae includes viruses that have different virion structures and morphogenesis mechanisms. Most cellular and molecular studies have been so far performed with viruses of the Hepacivirus and Flavivirus genera. Here, we studied bovine viral diarrhea virus (BVDV), a member of the Pestivirus genus. We set up a method to purify BVDV virions and analyzed their morphology by electron microscopy and their protein and lipid composition by mass spectrometry. Cryo-electron microscopy showed near spherical viral particles displaying an electron-dense capsid surrounded by a phospholipid bilayer with no visible spikes. Most particles had a diameter of 50 nm and about 2% were larger with a diameter of up to 65 nm, suggesting some size flexibility during BVDV morphogenesis. Morphological and biochemical data suggested a low envelope glycoprotein content of BVDV particles, E1 and E2 being apparently less abundant than Erns. Lipid content of BVDV particles displayed a ~2.3 to 3.5-fold enrichment in cholesterol, sphingomyelin and hexosyl-ceramide, concomitant with a 1.5 to 5-fold reduction of all glycerophospholipid classes, as compared to lipid content of MDBK cells. Although BVDV buds in the endoplasmic reticulum, its lipid content differs from a typical endoplasmic reticulum membrane composition. This suggests that BVDV morphogenesis includes a mechanism of lipid sorting. Functional analyses confirmed the importance of cholesterol and sphingomyelin for BVDV entry. Surprisingly, despite a high cholesterol and sphingolipid content of BVDV envelope, E2 was not found in detergent-resistant membranes. Our results indicate that there are differences between the structure and molecular composition of viral particles of Flaviviruses, Pestiviruses and Hepaciviruses within the Flaviviridae family. Bovine viral diarrhea virus (BVDV) is the etiologic agent of mucosal disease and bovine viral diarrhea, two economically important diseases of the livestock. BVDV is a member of the Pestivirus genus in the Flaviviridae family, which also includes Hepacivirus and Flavivirus genera. Members of this family share similar genome organization and replication strategies, but differ about their mode of transmission and particle structure. Whereas most studies have been so far performed on viruses of the Hepacivirus and Flavivirus genera, little is known about infectious particles of pestiviruses. In this study, we set up a novel purification method of BVDV infectious particles and analyzed their morphology by cryo-electron microscopy and their molecular composition by mass spectrometry. Our results provide new insights into the structure and biochemical composition of a pestivirus infectious particle, and have implications for research on molecular mechanisms of their morphogenesis and entry.
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Affiliation(s)
- Nathalie Callens
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Britta Brügger
- Heidelberg University Biochemistry Center, INF 328, Heidelberg, Germany
| | - Pierre Bonnafous
- Institut de Chimie et Biologie des Membranes et des Nano-objets, CNRS UMR-5248, Université de Bordeaux, Pessac, France
| | - Hervé Drobecq
- Univ. Lille, CNRS, Institut Pasteur de Lille, UMR 8161-M3T-Mechanisms of Tumorigenesis and Target Therapies, Lille, France
| | - Mathias J Gerl
- Heidelberg University Biochemistry Center, INF 328, Heidelberg, Germany
| | - Thomas Krey
- Institut Pasteur, Unité de Virologie Structurale, Département de Virologie, Paris, France.,CNRS UMR 3569, 25-28 Rue du Docteur Roux, Paris Cedex 15, France
| | - Gleyder Roman-Sosa
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut (FLI), 17493 Greifswald-Insel Riems, Germany
| | - Till Rümenapf
- Institute of Virology, University of Veterinary Medicine, Vienna, Austria
| | - Olivier Lambert
- Institut de Chimie et Biologie des Membranes et des Nano-objets, CNRS UMR-5248, Université de Bordeaux, Pessac, France
| | - Jean Dubuisson
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, Lille, France
| | - Yves Rouillé
- Univ. Lille, CNRS, Inserm, CHU Lille, Institut Pasteur de Lille, U1019-UMR 8204-CIIL-Center for Infection and Immunity of Lille, Lille, France
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Abstract
Syndromes resulting in Disorders of Sex Development (DSD) are individually rare. Historically, this fact has hindered both clinical research and the delivery of evidence-based care. Recognizing the need for advancement, members of European and North American medical societies produced policy statements, notably the Consensus Statement on Management of Intersex Disorders, which recognize that optimal healthcare in DSD requires multidisciplinary teams in conjunction with networking of treatment centers and continued development of patient registries. This paper summarizes efforts in Europe and the U.S. toward creating networks focused on expanding discovery and improving healthcare and quality of life outcomes in DSD. The objectives and function of registry-based networks (EuroDSD/I-DSD), learning collaboratives (DSD-net), clinical outcomes research (DSD-Life), and networking hybrids (DSD-TRN) are reviewed. Opportunities for, and barriers to standardization in research and care are highlighted in light of practical considerations, for example, limitations in reliably classifying anatomic phenotypes and gaps in behavioral health staffing resources. The role of patient-reported outcomes is considered, with emphasis on integrating patient perspectives, given findings of limited agreement in outcome ratings by healthcare providers and patients. Finally, the characteristics of clinical centers likely to deliver the highest quality outcomes are discussed.
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Affiliation(s)
- D E Sandberg
- Department of Pediatrics & Communicable Diseases and the Child Health Evaluation and Research (CHEAR) Unit, University of Michigan Medical School, Ann Arbor, USA
| | - N Callens
- Department of Pediatrics & Communicable Diseases and the Child Health Evaluation and Research (CHEAR) Unit, University of Michigan Medical School, Ann Arbor, USA
| | - A B Wisniewski
- Department of Urology, University of Oklahoma Health Sciences Center, Oklahoma City, USA
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Popescu CI, Callens N, Trinel D, Roingeard P, Moradpour D, Descamps V, Duverlie G, Penin F, Héliot L, Rouillé Y, Dubuisson J. NS2 protein of hepatitis C virus interacts with structural and non-structural proteins towards virus assembly. PLoS Pathog 2011; 7:e1001278. [PMID: 21347350 PMCID: PMC3037360 DOI: 10.1371/journal.ppat.1001278] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 01/07/2011] [Indexed: 02/07/2023] Open
Abstract
Growing experimental evidence indicates that, in addition to the physical virion components, the non-structural proteins of hepatitis C virus (HCV) are intimately involved in orchestrating morphogenesis. Since it is dispensable for HCV RNA replication, the non-structural viral protein NS2 is suggested to play a central role in HCV particle assembly. However, despite genetic evidences, we have almost no understanding about NS2 protein-protein interactions and their role in the production of infectious particles. Here, we used co-immunoprecipitation and/or fluorescence resonance energy transfer with fluorescence lifetime imaging microscopy analyses to study the interactions between NS2 and the viroporin p7 and the HCV glycoprotein E2. In addition, we used alanine scanning insertion mutagenesis as well as other mutations in the context of an infectious virus to investigate the functional role of NS2 in HCV assembly. Finally, the subcellular localization of NS2 and several mutants was analyzed by confocal microscopy. Our data demonstrate molecular interactions between NS2 and p7 and E2. Furthermore, we show that, in the context of an infectious virus, NS2 accumulates over time in endoplasmic reticulum-derived dotted structures and colocalizes with both the envelope glycoproteins and components of the replication complex in close proximity to the HCV core protein and lipid droplets, a location that has been shown to be essential for virus assembly. We show that NS2 transmembrane region is crucial for both E2 interaction and subcellular localization. Moreover, specific mutations in core, envelope proteins, p7 and NS5A reported to abolish viral assembly changed the subcellular localization of NS2 protein. Together, these observations indicate that NS2 protein attracts the envelope proteins at the assembly site and it crosstalks with non-structural proteins for virus assembly. Hepatitis C virus (HCV) causes major health problems worldwide. Understanding the major steps of the life cycle of this virus is essential to developing new and more efficient antiviral molecules. Virus assembly is the least understood step of the HCV life cycle. Growing experimental evidence indicates that, in addition to the physical virion components, the HCV non-structural proteins are intimately involved in orchestrating morphogenesis. Since it is dispensable for HCV RNA replication, the non-structural viral protein NS2 is suggested to play a central role in HCV particle assembly. Molecular interactions between NS2 and other HCV proteins were demonstrated. Furthermore, NS2 was shown to accumulate over time in endoplasmic reticulum-derived structures and to colocalize with the viral envelope glycoproteins and viral components of the replication complex in close proximity to the HCV core protein and lipid droplets. Importantly, specific mutations within NS2 that affected HCV infectivity could also alter the subcellular localization of NS2 protein and its interactions, suggesting that this subcellular localization and its interactions are essential for HCV particle assembly. Altogether, these observations indicate that NS2 protein plays an important role in connecting different viral components that are essential for virus assembly.
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Affiliation(s)
- Costin-Ioan Popescu
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- Institute of Biochemistry of the Romanian Academy, Bucharest, Romania
| | - Nathalie Callens
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Dave Trinel
- Institute of Interdisciplinary Research, University Lille 1, Villeneuve d'Ascq, France
| | - Philippe Roingeard
- INSERM U966, Université François Rabelais and CHRU de Tours, Tours, France
| | - Darius Moradpour
- Division of Gastroenterology and Hepatology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
| | - Véronique Descamps
- Laboratoire de Virologie, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - Gilles Duverlie
- Laboratoire de Virologie, Centre Hospitalier Universitaire d'Amiens, Amiens, France
| | - François Penin
- Institut de Biologie et Chimie des Protéines, UMR-5086-CNRS, Université de Lyon, Lyon, France
| | - Laurent Héliot
- Institute of Interdisciplinary Research, University Lille 1, Villeneuve d'Ascq, France
| | - Yves Rouillé
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
| | - Jean Dubuisson
- Inserm U1019, CNRS UMR8204, Center for Infection & Immunity of Lille (CIIL), Institut Pasteur de Lille, Université Lille Nord de France, Lille, France
- * E-mail:
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Ciczora Y, Callens N, Séron K, Rouillé Y, Dubuisson J. Identification of a dominant endoplasmic reticulum-retention signal in yellow fever virus pre-membrane protein. J Gen Virol 2009; 91:404-14. [PMID: 19846669 DOI: 10.1099/vir.0.015339-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Yellow fever virus (YFV) encodes two envelope proteins, pre-membrane (prM) and envelope (E), that accumulate in the endoplasmic reticulum (ER). The C termini of prM and E form two antiparallel transmembrane alpha-helices that contain ER-retention signals. To understand further the ER retention of the prME heterodimer, we characterized the subcellular localization of chimeric proteins made of a reporter protein fused to the transmembrane segments of YFV envelope proteins. We showed that at least three of the transmembrane segments of the prME heterodimer are ER-retention signals. Interestingly, increasing the length of these alpha-helices led to the export of the chimeric proteins out of the ER. Furthermore, adding a diacidic export signal at the C terminus of the first transmembrane segment of the E protein also induced export to the cell surface. However, adding this export signal at the C terminus of the first transmembrane segment of E in the context of prME did not change the subcellular localization of the prME heterodimer, suggesting the presence of a stronger ER-retention signal outside the first transmembrane segment of E. Importantly, the diacidic export motif added to the C terminus of the first transmembrane segment of the prM protein was not sufficient to export a chimeric protein out of the ER, indicating that this sequence is a dominant ER-retention signal. Together, these data indicate that a combination of several signals of different strengths contributes to the ER retention of the YFV envelope protein heterodimer.
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Affiliation(s)
- Yann Ciczora
- Université Lille Nord de France, F-59000 Lille, France
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Ciczora Y, Callens N, Penin F, Pécheur EI, Dubuisson J. Transmembrane domains of hepatitis C virus envelope glycoproteins: residues involved in E1E2 heterodimerization and involvement of these domains in virus entry. J Virol 2006; 81:2372-81. [PMID: 17166909 PMCID: PMC1865936 DOI: 10.1128/jvi.02198-06] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The transmembrane (TM) domains of hepatitis C virus (HCV) envelope glycoproteins E1 and E2 have been shown to play multiple roles during the biogenesis of the E1E2 heterodimer. By using alanine scanning insertion mutagenesis within the TM domains of HCV envelope glycoproteins, we have previously shown that the central regions of these domains as well as the N-terminal part of the TM domain of E1 are involved in heterodimerization. Here, we used a tryptophan replacement scan of these regions to identify individual residues that participate in those interactions. Our mutagenesis study identified at least four residues involved in heterodimerization: Gly 354, Gly 358, Lys 370, and Asp 728. Interestingly, Gly 354 and Gly 358 belong to a GXXXG oligomerization motif. Our tryptophan mutants were also used to generate retrovirus-based, HCV-pseudotyped particles (HCVpp) in order to analyze the effects of these mutations on virus entry. Surprisingly, two mutants consistently displayed higher infectivity compared to that of the wild type. In contrast, HCVpp infectivity was strongly affected for many mutants, despite normal E1E2 heterodimerization and normal levels of incorporation of HCV glycoproteins into HCVpp. The characterization of some of these HCVpp mutants in the recently developed in vitro fusion assay using fluorescent-labeled liposomes indicated that mutations reducing HCVpp infectivity without altering E1E2 heterodimerization affected the fusion properties of HCV envelope glycoproteins. In conclusion, this mutational analysis identified residues involved in E1E2 heterodimerization and revealed that the TM domains of HCV envelope glycoproteins play a major role in the fusion properties of these proteins.
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Affiliation(s)
- Yann Ciczora
- Hepatitis C Laboratory, CNRS-UMR8161, Institut de Biologie de Lille, 1 rue Calmette, BP447, 59021 Lille cedex, France
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8
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Callens N, Ciczora Y, Bartosch B, Vu-Dac N, Cosset FL, Pawlotsky JM, Penin F, Dubuisson J. Basic residues in hypervariable region 1 of hepatitis C virus envelope glycoprotein e2 contribute to virus entry. J Virol 2006; 79:15331-41. [PMID: 16306604 PMCID: PMC1316016 DOI: 10.1128/jvi.79.24.15331-15341.2005] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The N terminus of hepatitis C virus (HCV) envelope glycoprotein E2 contains a hypervariable region (HVR1) which has been proposed to play a role in viral entry. Despite strong amino acid variability, HVR1 is globally basic, with basic residues located at specific sequence positions. Here we show by analyzing a large number of HVR1 sequences that the frequency of basic residues at each position is genotype dependent. We also used retroviral pseudotyped particles (HCVpp) harboring genotype 1a envelope glycoproteins to study the role of HVR1 basic residues in entry. Interestingly, HCVpp infectivity globally increased with the number of basic residues in HVR1. However, a shift in position of some charged residues also modulated HCVpp infectivity. In the absence of basic residues, infectivity was reduced to the same level as that of a mutant deleted of HVR1. We also analyzed the effect of these mutations on interactions with some potential HCV receptors. Recognition of CD81 was not affected by changes in the number of charged residues, and we did not find a role for heparan sulfates in HCVpp entry. The involvement of the scavenger receptor class B type I (SR-BI) was indirectly analyzed by measuring the enhancement of infectivity of the mutants in the presence of the natural ligand of SR-BI, high-density lipoproteins (HDL). However, no correlation between the number of basic residues within HVR1 and HDL enhancement effect was observed. Despite the lack of evidence of the involvement of known potential receptors, our results demonstrate that the presence of basic residues in HVR1 facilitates virus entry.
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Affiliation(s)
- Nathalie Callens
- Unité Hépatite C, CNRS-UPR2511, Institut de Biologie de Lille, 1 rue Calmette, BP447, 59021 Lille cedex, France
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9
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Ciczora Y, Callens N, Montpellier C, Bartosch B, Cosset FL, De Beeck AO, Dubuisson J. Contribution of the charged residues of hepatitis C virus glycoprotein E2 transmembrane domain to the functions of the E1E2 heterodimer. J Gen Virol 2005; 86:2793-2798. [PMID: 16186234 DOI: 10.1099/vir.0.81140-0] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The envelope glycoproteins of Hepatitis C virus (HCV), E1 and E2, form a heterodimer that is retained in the endoplasmic reticulum (ER). The transmembrane (TM) domains play a major role in E1E2 heterodimerization and in ER retention. Two fully conserved charged residues in the middle of the TM domain of E2 (Asp and Arg) are crucial for these functions. Replacement of the Asp residue by a Leu impaired E1E2 heterodimerization, whereas the Arg-to-Leu mutation had a milder effect. Both Asp and Arg residues were shown to contribute to the ER retention function of E2. In addition, the entry function of HCV envelope glycoproteins was affected by these mutations. Together, these data indicate that the charged residues present in the TM domain of E2 play a major role in the biogenesis and the entry function of the E1E2 heterodimer. However, the Asp and Arg residues do not contribute equally to these functions.
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Affiliation(s)
- Yann Ciczora
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Nathalie Callens
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Claire Montpellier
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Birke Bartosch
- Laboratoire de Vectorologie Rétrovirale et Thérapie Génique, INSERM U412, IFR74, Ecole Normale Supérieure de Lyon, Lyon, France
| | - François-Loïc Cosset
- Laboratoire de Vectorologie Rétrovirale et Thérapie Génique, INSERM U412, IFR74, Ecole Normale Supérieure de Lyon, Lyon, France
| | - Anne Op De Beeck
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
| | - Jean Dubuisson
- CNRS-UPR2511, Unité Hépatite C, Institut de Biologie de Lille - Institut Pasteur de Lille, 1 rue Calmette, BP 447, 59021 Lille cedex, France
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Goffard A, Callens N, Bartosch B, Wychowski C, Cosset FL, Montpellier C, Dubuisson J. Role of N-linked glycans in the functions of hepatitis C virus envelope glycoproteins. J Virol 2005; 79:8400-9. [PMID: 15956584 PMCID: PMC1143753 DOI: 10.1128/jvi.79.13.8400-8409.2005] [Citation(s) in RCA: 200] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Hepatitis C virus (HCV) encodes two viral envelope glycoproteins. E1 contains 4 or 5 N-linked glycosylation sites and E2 contains up to 11, with most of the sites being well conserved, suggesting that they play an essential role in some functions of these proteins. For this study, we used retroviral pseudotyped particles harboring mutated HCV envelope glycoproteins to study these glycans. The mutants were named with an N followed by a number related to the relative position of the potential glycosylation site in each glycoprotein (E1N1 to E1N4 for E1 mutants and E2N1 to E2N11 for E2 mutants). The characterization of these mutants allowed us to define three phenotypes. For the first group (E1N3, E2N3, E2N5, E2N6, E2N7, and E2N9), the infectivities of the mutants were close to that of the wild type. The second group (E1N1, E1N2, E1N4, E2N1, and E2N11) contained mutants that were still infectious but whose infectivities were reduced to <50% that of the wild type. The third group (E2N2, E2N4, E2N8, and E2N10) contained mutants that had almost totally lost infectivity. The absence of infectivity of the E2N8 and E2N10 mutants was due to the lack of incorporation of the E1E2 heterodimer into HCVpp, which was due to misfolding of the heterodimer, as shown by immunoprecipitation with conformation-sensitive antibodies and by a CD81 pull-down assay. The absence of infectivity of the E2N2 and E2N4 mutants indicated that these two glycans are involved in controlling HCV entry. Altogether, the data indicate that some glycans of HCV envelope glycoproteins play a major role in protein folding and others play a role in HCV entry.
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Affiliation(s)
- Anne Goffard
- CNRS-UPR2511, Institut de Biologie de Lille, France
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Voisset C, Callens N, Blanchard E, Op De Beeck A, Dubuisson J, Vu-Dac N. High density lipoproteins facilitate hepatitis C virus entry through the scavenger receptor class B type I. J Biol Chem 2005; 280:7793-9. [PMID: 15632171 DOI: 10.1074/jbc.m411600200] [Citation(s) in RCA: 182] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The scavenger receptor class B type I (SR-BI) has recently been shown to interact with hepatitis C virus (HCV) envelope glycoprotein E2, suggesting that it might be involved at some step of HCV entry into host cells. However, due to the absence of a cell culture system to efficiently amplify HCV, it is not clear how SR-BI contributes to HCV entry. Here, we sought to determine how high density lipoproteins (HDLs), the natural ligand of SR-BI, affect HCV entry. By using the recently described infectious HCV pseudotyped particles (HCVpps) that display functional E1E2 glycoprotein complexes, we showed that HDLs are able to markedly enhance HCVpp entry. We did not find any evidence of HDL association with HCVpps, suggesting that HCVpps do not enter into target cells using HDL as a carrier to bind to its receptor. Interestingly, lipid-free apoA-I and apoA-II, the major HDL apolipoproteins, were unable to enhance HCVpp infectivity. In addition, drugs inhibiting HDL cholesteryl transfer (block lipid transport (BLT)-2 and BLT-4) reduced HDL enhancement of HCVpp entry, suggesting a role for lipid transfer in facilitating HCVpp entry. Importantly, silencing of SR-BI expression in target cells by RNA interference markedly reduced HDL-mediated enhancement of HCVpp entry. Finally, enhancement of HCVpp entry was also suppressed when the SR-BI binding region on HCV glycoprotein E2 was deleted. Altogether, these data indicate that HDL-mediated enhancement of HCVpp entry involves a complex interplay between SR-BI, HDL, and HCV envelope glycoproteins, and they highlight the active role of HDLs in HCV entry.
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Affiliation(s)
- Cécile Voisset
- CNRS-UPR2511, Institut de Biologie de Lille and Institut Pasteur de Lille, Lille 59021, France
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Callens N, Baert JL, Monté D, Sunesen M, Van Lint C, de Launoit Y. Transcriptional regulation of the murine brca2 gene by CREB/ATF transcription factors. Biochem Biophys Res Commun 2004; 312:702-7. [PMID: 14680822 DOI: 10.1016/j.bbrc.2003.10.176] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2003] [Indexed: 11/28/2022]
Abstract
The brca2 gene encodes a nuclear protein which is mainly involved in DNA repair and, when mutated, is responsible for some of the hereditary breast cancers. However, brca2 expression is also deregulated in sporadic breast tumors. In the mouse brca2 gene we had earlier identified a region of 148bp upstream of the transcription start site sufficient to activate its expression. In the present report, we show that the -92 to -40bp region is essential for the transcription of brca2 in murine mammary cells and that this nucleotide sequence contains one putative CREB/ATF consensus site (cAMP responsive element: CRE). We demonstrated that the mutation of this binding site led to a highly significant reduction of the mouse brca2 transcription, and that CREB, CREM, and/or ATF-1 functionally bound to and regulated this promoter. Therefore, the regulation of the promoter of the mouse brca2 gene is driven by this family of transcription factors.
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Affiliation(s)
- Nathalie Callens
- UMR 8117 CNRS, Institut Pasteur de Lille, Université de Lille 1, Institut de Biologie de Lille, BP 447, 1 rue Calmette, 59021 Lille Cedex, France
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Maurer P, T'Sas F, Coutte L, Callens N, Brenner C, Van Lint C, de Launoit Y, Baert JL. FEV acts as a transcriptional repressor through its DNA-binding ETS domain and alanine-rich domain. Oncogene 2003; 22:3319-29. [PMID: 12761502 DOI: 10.1038/sj.onc.1206572] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although most Ets transcription factors have been characterized as transcriptional activators, some of them display repressor activity. Here we characterize an Ets-family member, the very specifically expressed human Fifth Ewing Variant (FEV), as a transcriptional repressor. We show that among a broad range of human cell lines, only Dami megakaryocytic cells express FEV. This nuclear protein binds to Ets-binding sites, such as that of the human ICAM-1 promoter. We used this promoter to demonstrate that FEV can repress both basal transcription and, even more strongly, ectopically Ets-activated transcription. We identified two domains responsible for FEV-mediated repression: the ETS domain, responsible for passive repression, and the carboxy-terminal alanine-rich domain, involved in active repression. In the Ets-independent LEXA system also, FEV acts as a transcriptional repressor via its alanine-rich carboxy-terminal domain. The mechanism by which FEV actively represses transcription is currently unknown, since FEV-triggered repression is not reversed by the histone deacetylase inhibitor trichostatin A. We also showed that long-term overexpression of FEV proteins containing the alanine-rich domain prevents cell clones from growing, whereas clones expressing a truncated FEV protein lacking this domain develop like control cells. This confirms the importance of this domain in FEV-triggered repression.
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Affiliation(s)
- Philippe Maurer
- 1Laboratoire de Virologie Moléculaire, Faculté de Médecine, Université Libre de Bruxelles, CP 614, 808 route de Lennik, 1070 Brussels, Belgium
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Callens N, Dumont M, Begue A, Lint C, Baert JL, Simard J, de Launoit Y. Genomic organization and expression of the mouse Brca2 gene. Mamm Genome 2002; 13:352-8. [PMID: 12140683 DOI: 10.1007/s00335-002-2300-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2002] [Accepted: 03/21/2002] [Indexed: 11/29/2022]
Abstract
A mutation of the Brca2 gene product is responsible for a large proportion of the inherited breast cancers. Here, we have demonstrated that the mouse Brca2 gene is composed of 27 exons and 26 introns, spanning approximately 48 kbp, almost all intron-exon junctions being classical. The overall mouse Brca2 gene structure is highly similar in the coding sequences to that of the human gene. The predicted 11-kb transcript is predominantly present in testis, spleen, thymus, epididymis, and seminal vesicles. A smaller-size, strong positive hybridization signal, which was obtained by using 5' end exons as probes, is ubiquitously observed in mouse tissues. The exact origin and function of this small transcript is currently unknown. The transcription start site of this gene has been identified at approximately 300 bp upstream from the translation initiation codon, and the first 148 bp proximal TATA-less promoter region is sufficient to activate maximal transcription of this gene in mammary cells.
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Affiliation(s)
- Nathalie Callens
- Laboratoire de Virologie Moléculaire--Faculté de Médecine, Université Libre de Bruxelles, CP 614, 808 route de Lennik, 1070 Brussels, Belgium
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